Carrier aggregation is a technique where a base station aggregates transmissions to a terminal on multiple carriers, possibly on adjacent carriers on the same frequency band, on non-adjacent carriers on the same frequency band, or on carriers on different frequency bands. Carrier aggregation is also a technique, where a terminal aggregates transmissions to a base station on multiple carriers, possibly on adjacent carriers on the same frequency band, on non-adjacent carriers on the same frequency band, or on carriers on different frequency bands. The aggregated transmissions may include single or multiple mutually different radio access technologies.